The present invention relates to fiber forming synthetic linear polyamides having exceptional dimensional stability comprising polyamides formed by condensation of amide-forming compounds, comprising cyclohexanebis(ethylamine)
Polyamides derived from cyclohexanebis (methylamine) are known in the prior art. In U.S. Pat. No. 3,012,994 polyamides derived from the condensation of 1,3- or 1,4-cyclohexanebis(methylamine) and a dicarboxylic acid are described. These polyamides possess good stability and strength properties and are described as having relatively high melting points; for example, the polyamide of trans-1, 4cyclohexane-bis(methylamine) and adipic acid has a crystalline melting point of 345.degree. C., whereas nylon 66 formed from hexamethylene diamine and adipic acid has a melting point of only 264.degree. C. However, the high melting point advantage of these polyamides also gives rise to certain inherent disadvantages. For example, polyamides having crystalline melting points much above about 300.degree. C. tend to decompose into degradation products prior to melting. As a result filaments formed from these high melting polyamides generally have poor processability and inferior properties. Although lower melting polyamides can be obtained with trans-1,4cyclohexanebis(methylamine) by condensation with longer chain carboxylic acids, the use of the longer chain acids results in a decrease in the dimensional stability of the resulting polyamide. An object of the present invention is to provide polyamides derived from components comprising a cyclohexanebis(alkylamine) which have good dimensional stability and which have substantially lower melting points than the corresponding polyamides derived from cyclohexanebis(methylamine).